Seminal fluid factor increases the resistance of the tight junctional complex of cultured human cervical epithelium CaSki cells

OBJECTIVE

To determine the effects of human seminal fluid on cervical paracellular resistance.

DESIGN

Experimental study.

SETTING

Healthy volunteers in an academic research environment; cultures of human CaSki cells on filters, with phenotypic characteristics of the endocervix.

PATIENT(S)

Healthy men donating sperm to a sperm bank.

INTERVENTION(S)

Seminal fluid was obtained as the discarded fluid from ejaculates.

MAIN OUTCOME MEASURE(S)

Changes in transepithelial electrical resistance across CaSki cells on filters were determined in an Ussing chamber from successive measurements of the short-circuit current and the transepithelial potential difference. Changes in the dilution potential (and hence in the ratio of Cl- to Na+ mobilities) were determined after lowering the NaCl concentration in the luminal solution.

RESULT(S)

Seminal fluid increased transepithelial electrical resistance acutely (t1/2, 2 minutes), reversibly, and in a dose-related manner (ED50, 1%). The effect of seminal fluid was abolished when the extracellular calcium level was lowered, and the increase in transepithelial electrical resistance correlated with a decrease in the ratio Cl- to Na+ mobilities, indicating an increase in the resistance of the tight junctional complex. The increase in transepithelial electrical resistance in response to seminal fluid was nonadditive to that of sn-1,2-dioctanoyl diglyceride (a stable diacylglyceride and activator of protein kinase C), and it was abolished by prolonged preincubation with the phorbol ester phorbol 12-myristate 13-acetate (to downregulate protein kinase C) or with staurosporin (to inhibit protein kinase C), suggesting that seminal fluid acts through a protein kinase C-dependent mechanism. Slower (t1/2, 3.3 minutes) increases in transepithelial electrical resistance occurred when seminal fluid was added only to the luminal or the subluminal solution. Treatment with pertussis toxin, adenosine triphosphatase, or trypsin had no effect on the changes in transepithelial electrical resistance. Seminal fluid increased cytosolic calcium, but changes in cytosolic calcium are not important for the increases in transepithelial electrical resistance, suggesting that the effect of seminal fluid is not receptor-mediated. Preliminary studies indicate that the factor(s) in seminal fluid that increases transepithelial electrical resistance is a labile, low molecular weight (< 10 kd) lipid.

CONCLUSION(S)

Seminal fluid may regulate cervical mucus production in vivo by modulating endocervical permeability.

The meiotic competence of in-vitro matured human oocytes is influenced by donor age: evidence that folliculogenesis is compromised in the reproductively aged ovary

The human oocyte appears to be particularly prone to meiotic errors, and the incidence of these errors is strongly influenced by maternal age. We have initiated studies of human oocytes from unstimulated ovaries and have observed age-related effects on the meiotic process in oocytes from unselected antral follicles. Specifically, in oocytes obtained from donors over the age of 35 years, the majority of oocytes that extruded a first polar body in culture and arrested at second meiotic metaphase had aberrations in spindle formation and chromosome alignment. Similarly, observations of a limited number of oocytes at first meiotic metaphase suggest disturbances at this stage of meiosis as well. Finally, preliminary results of non-disjunction studies suggest that the frequency of errors in chromosome segregation at the first meiotic division is influenced by donor age in in-vitro matured oocytes as it is in oocytes undergoing meiotic maturation in vivo. These data provide direct evidence that the meiotic competence of oocytes from unstimulated ovaries declines with donor age. Similarly, studies of in-vitro fertilization (IVF) pregnancies in older women indicate that the developmental competence of the human oocyte declines with age. Since both meiotic and developmental competence are acquired during the late stages of oocyte growth, we postulate that an age-related decline in the process of folliculogenesis results in reduced oocyte quality and that the well characterized age-related increase in meiotic non-disjunction is one symptom of compromised oocyte growth.

Effects of subinguinal varicocele ligation on sperm concentration, motility and Kruger morphology

PURPOSE

We examined the effects of varicocelectomy on semen parameters in 30 subfertile men, with emphasis on potential changes in sperm count, motility and morphology as measured by Kruger's strict morphologic criteria.

MATERIALS AND METHODS

A total of 30 patients underwent subinguinal varicocelectomy (25 bilateral and 5 unilateral). Preoperative and postoperative sperm density, motility and morphology were analyzed. Preoperative follicle-stimulating hormone, luteinizing hormone and testosterone levels were measured and compared to those of fertile volunteers enrolled in our sperm donation program. Pregnancy rates after varicocelectomy were also examined: The Wilcoxon signed rank test was used to measure levels of statistical significance in all analyses.

RESULTS

We found that sperm density and motility improved significantly (p < 0.05) without concomitant changes in strict morphology (p > 0.05) only in men with clinical bilateral varicoceles. No differences were observed in values among testosterone, follicle-stimulating hormone and luteinizing hormone levels of the fertile control group and preoperative varicocele patients. Of 30 patients 12 (40%) had successful, full-term pregnancies, including 6 via natural cycle intercourse, 5 (43%) by in vitro fertilization embryo transfer and 1 by intracytoplasmic sperm injection.

CONCLUSIONS

Although sperm morphology as measured by strict morphologic criteria does not improve after varicocelectomy, there were highly significant changes in motility and concentration. Hormonal differences are not likely to have a role in or be reflective of pathophysiology of varicocele induced male infertility. The recent observation that sperm motility may be an independent or additive predictive factor for fertilization and pregnancy supports the need for continued varicocele repair independent of the lack of varicocelectomy effect on Kruger morphology.

Factors influencing patients' decision not to repeat IVF

Women who did not pursue a second in vitro fertilization cycle after a failed cycle were surveyed. The major reason for not pursuing a second cycle was financial.

Extracellular ATP regulates transcervical permeability by modulating two distinct paracellular pathways

Extracellular ATP stimulates a biphasic change in transepithelial electrical resistance (RTE) across cultures of human cervical epithelial cells: an acute decrease (phase I), followed by a delayed increase in resistance (phase II). The objective of this study was to determine the contributions of changes in the lateral intercellular space resistance (RLIS) and the tight junctional resistance (RTJ) to the changes in RTE. Phase I and phase II effects were uncoupled by treatment with 1,2-bis(2-aminophenoxy) ethane-N,N,N',N'-tetraacetic acid (BAPTA)-acetoxymethyl ester, which blocks the ATP-induced increases in cytosolic Ca2+ and abolishes phase I. BAPTA-loaded cells differed from control cells in that 1) phase I began when ATP was added, in contrast to a delay of 1.5-3.5 min in phase II, 2) phase I decreases in RLIS followed a simple exponential pattern, in contrast to the complex kinetics of phase II, and 3) the magnitude of phase II varied between 20 and 100% for increases of RTJ in day 2-6 cultures; the phase I decrease of 50% in RLIS was unrelated to different experimental conditions. These results indicate that phase I and phase II are induced simultaneously and independently by ATP, and they contribute to the total changes in RTE. We conclude that ATP regulation of RLIS and RTJ may be important mechanisms of modulating cervical mucus production in vivo.

Use of Synthetic Serum Substitute and alpha-minimum essential medium for the extended culture of human embryos to the blastocyst stage

This study was designed to provide further information on mouse and human embryo development in alpha-modified minimum essential medium (alphaMEM). First, we compared the development and implantation potential of murine in-vitro fertilized (IVF) embryos cultured in alphaMEM, in the presence and absence of co-culture cells. No significant difference was observed in blastocyst rate between alphaMEM alone (76.2%) and alphaMEM plus co-culture (79.9%). The percentage of hatched blastocysts was, however, higher with co-culture (47.5 versus 40%, P < 0.01). Transfer of blastocysts to pseudopregnant foster mothers resulted in similar live birth rates (14.9% alphaMEM alone versus 19.8% alphaMEM/co-culture). alphaMEM was also introduced into our clinical IVF programme for culture of human embryos beyond day 3. Spare human embryos were cultured under oil in microdrops of alphaMEM supplemented with 10% synthetic serum substitute. Blastocysts were evaluated for maturity and the presence and organization of the inner cell mass. A total of 206 embryos from 53 IVF patients underwent extended culture. The overall blastocyst rate was 45.1%. An inner cell mass was observed in 76 blastocysts (81.7%). With regard to developmental maturity, approximately 73% of blastocysts that had been frozen were expanding (cavity > 50% embryo volume) or fully expanded. These data suggest that alphaMEM in conjunction with a commercial protein preparation such as Synthetic Serum Substitute may be a good basal medium for culture of human embryos to the blastocyst stage.

Comparison study of the immunogenicity and safety of 5- and 10-microgram dosages of a recombinant hepatitis B vaccine in healthy infants

BACKGROUND

It has been suggested that lower dosages of hepatitis B vaccine may be adequate for vaccinating infants and would be less costly.

OBJECTIVES

To compare the immunogenicity and safety of 5 and 10 micrograms of Engerix-B recombinant hepatitis B vaccine given to healthy infants.

METHODS

A prospective randomized comparison of 5- and 10-micrograms doses of Engerix-B recombinant hepatitis B vaccine given to infants at 2, 4 and 6 months of age. Seroconversion (antihepatitis B surface antigen (anti-HBs) > or = 1 mIU/ ml) and seroprotection (anti-HBs > or = 10 mIU/ml) rates as well as geometric mean antibody titers were compared at 4, 6 and 8 months.

RESULTS

A total of 190 healthy infants were screened and received the first dose of vaccine. Of these infants 153 were eligible to continue in the study. Both dosages proved to be highly immunogenic, producing high seroconversion and seroprotection rates and geometric mean anti-HBs concentrations after 3 doses. Although 10 micrograms induced significantly greater geometric mean concentrations (1641 mIU/ml compared 880 mIU/ml at 8 months of age), the seroprotection rates were identical (98.5%).

CONCLUSIONS

Both dosages were well-tolerated and no serious adverse experiences were reported. However, the 5 micrograms of Engerix-B administered at 2, 4 and 6 months of age did not induce as great an anti-Hbs concentration as did 10 micrograms. Long term studies are required to determine whether using the lower dosage would sacrifice long term efficacy.

Comparison study of the immunogenicity and safety of 5- and 10-microgram dosages of a recombinant hepatitis B vaccine in healthy children

OBJECTIVE

To compare the immunogenicity and safety of 5 micrograms with 10 micrograms of Engerix-B recombinant hepatitis B vaccine when given to healthy children, 2 to 6 years of age.

METHODS

Randomized multicenter study of serongative children 2 to 6 years of age who received Engerix-B hepatitis B vaccine either 5 micrograms/0.25 ml or 10 micrograms/0.5 ml (the current Food and Drug Administration-approved dosage of Engerix-B in children) at 0, 1 and 6 months. Serum was obtained at 1, 3, 6 and 8 months after the first vaccine dose was given for antibody measurement.

RESULTS

A total of 223 subjects were screened and received the first dose of vaccine. Of these subjects 193 continued in the study. Both dosages proved to be highly immunogenic, producing high seroconversion and seroprotection rates and geometric mean antibody to hepatitis B surface antigen concentrations after 3 doses. The geometric mean concentrations of seroconverters at Months 6 and 8 were significantly greater for the 10-micrograms group compared with the 5-micrograms group. Both dosages were well-tolerated and no serious adverse events were reported.

CONCLUSIONS

There was a significant reduction in geometric mean concentrations on lowering the dosage of Engerix-B from 10 to 5 micrograms in children 2 to 6 years of age. Although a high seroprotection rate was elicited by the 5-micrograms dose, the lower antibody concentrations achieved may make this lower dosage less desirable in the long term. Further studies are required to examine the need for booster doses of vaccine with both dosing schedules.

What went wrong: multiple perspectives on an adolescent's decision to refuse blood transfusions

Persons with religious beliefs that conflict with mainstream medical practice create a tension for clinicians between honoring the different religious perspectives of the individual or carrying out what they believe to be their professional obligation. This is a patient presentation of an adolescent Jehovah's Witness who refuses blood transfusions. The major issue in this patient is the conflict among three values (1) respect for religious beliefs, (2) respect for a competent person's right to refuse treatment, and (3) the ability of an adolescent to make good decisions for himself. Other dilemmas presented by this patient are the lack of a coordinated plan of care, the lack of communication with the patient and family, and the lack of attention to social factors that influence the patient's situation and his resulting care.

Attitudes of in vitro fertilization and intrauterine insemination couples toward multiple gestation pregnancy and multifetal pregnancy reduction

OBJECTIVE

To determine attitudes regarding multiple pregnancy and multifetal pregnancy reduction in couples embarking on gonadotropin therapy.

DESIGN

Questionnaire given to couples initiating gonadotropin therapy.

SETTING

University hospital-based infertility unit.

PATIENTS

Twenty-seven couples undergoing IVF and 50 couples undergoing IUI.

RESULTS

The groups' responses tended to be quite similar, with all groups reporting declining favorability ratings as the fetal order increased. The IUI group did feel more favorable than the IVF group toward all gestational outcomes and less favorable toward multifetal pregnancy reduction. A history of live births and length of infertility had no significant impact on the results.

CONCLUSION

Couples undergoing gonadotropin therapy have an overall favorable attitude toward multiple gestational pregnancies of triplets or twins and an increased willingness to consider multifetal pregnancy reduction for quadruplets and more.

Effects of estrogen in vivo on coronary vascular resistance in perfused rabbit hearts

Estrogen or its vehicle was given daily to three groups of ovariectomized rabbits for various lengths of time, after which coronary flow was measured in their isolated perfused hearts. In one group, intramuscular injections of estrogen (40 micrograms/kg) for 7 or 14 days increased coronary flow by 40-50% (P < 0.05). In rabbits given estrogen intramuscularly for 7 days, the coronary flow returned to the basal level within 7 days after the estrogen injections were discontinued. In a second group of animals, intravenous injections of estrogen (10 micrograms/kg) for 4 days increased the coronary flow by 45% (P < 0.01). In a third group, we administered the estrogen transdermally for 4 days, and we measured the plasma estrogen levels at the end of this period. The coronary flow in this group was increased by 52% (P < 0.001), and the plasma estrogen levels ranged from 39 to 800 pg/ml. In all groups of experiments, the increments in coronary flow evoked by estrogen were virtually abolished by NG-nitro-L-arginine, an inhibitor of nitric oxide synthase. We conclude that estrogen regulates coronary blood flow, in part by upregulating nitric oxide synthase in the coronary vasculature.

Osmolar changes regulate the paracellular permeability of cultured human cervical epithelium

Extracellular nucleotides induce a biphasic change in the transepithelial electrical conductance (GT) of human cervical cells grown on filters: a rapid increase (phase I) followed by a sustained decrease (phase II). To probe the involvement of the intercellular space, its magnitude was varied by manipulating cell volume through changes in extracellular osmolarity. Under baseline conditions [GT = 115 mS/cm2 (approximately 9 omega.cm2)] and during phase II, hypertonic challenges resulted in an increase in GT (0.98% .mosmol-1.l-1 and 0.73%.mosmol-1.l-1, respectively). However, a hypertonic challenge during phase I decreased GT (-0.16%.mosmol-1.l-1). Hypotonic challenges decreased GT during baseline, phase I, and phase II conditions by -1%.mosmol-1.l-1. Similar trends were observed with regard to pyranine permeability. Reduction of extracellular calcium increased GT, abrogated the phase II effect of extracellular ATP, and reversed the effect of a hypertonic challenge. The additive nature of the permeability changes in response to osmotic challenges and to ATP during phase II suggests that different sites are involved in each response, i.e., the resistance of the intercellular space changes with osmolarity and that of the tight junction during phase II.

Ceftibuten vs. penicillin V in group A beta-hemolytic streptococcal pharyngitis. Members of the Ceftibuten Pharyngitis International Study Group

The efficacy and safety of a 10-day course of ceftibuten oral suspension (9 mg/kg once daily) were compared with those of penicillin V (25 mg/kg/day in 3 divided doses) in children 3 to 18 years old treated for symptomatic pharyngitis and scarlet fever caused by group A beta-hemolytic streptococci (Streptococcus pyogenes). The study was prospective, randomized, multicenter and investigator-blinded; patients were randomized in a 2:1 ratio (ceftibuten:penicillin V). Overall clinical success (cure/improvement) at the primary end point of treatment (5 to 7 days posttherapy) was achieved in 97% (285 of 294) of ceftibuten-treated patients vs. 89% (117 of 132) of penicillin V-treated patients (P < 0.01). Elimination of infecting streptococci 5 to 7 days posttherapy was achieved in 91% (267 of 294) of ceftibuten-treated patients vs 80% (105 of 132) of penicillin V-treated patients (P < 0.01). A significant rise in anti-streptolysin O or anti-DNase B was observed in approximately 30% of patients in both treatment groups. No patient developed rheumatic fever or nephritis. Treatment-related adverse events were similar between the two groups; mild vomiting (2%) was most frequently reported. These data suggest that once daily ceftibuten is as safe as and more effective than three times daily penicillin V for the treatment of group A beta-hemolytic streptococcal pharyngitis.

New antimicrobial agents

In any discussion of new antimicrobial agents in the 1990s, a warning and a plea are necessary. The spreading emergence of resistance among bacteria raises concerns for the effectiveness of antimicrobial therapy. Penicillin-resistant pneumococci are probably of most significance in pediatrics and are increasing in frequency, in part related to the use of antimicrobial therapy in young children to treat such infections as otitis media. New practice guidelines have suggested the more limited use of antimicrobial agents in treating serious otitis media. When pediatricians do treat, they should select effective agents. Limiting therapy to brief courses with effective and narrow-spectrum agents may be helpful also. Treating long enough to ensure eradication in serious infections is equally important. Methicillin-resistant S aureus are also increasing and are increasingly a concern in community-acquired infections and nosocomial infections. Using topical agents, such as mupirocin, to treat impetigo and other superficial skin infections can limit exposure to systemic agents and may delay the spread of resistance. Vancomycin-resistant enterococcal infections, an infrequent pediatric problem, are most frightening because no alternative therapies are available. Their occurrence is directly related to use of vancomycin in the communities that are affected. Containing the spread of drug-resistant bacteria will likely require a concerted effort by both physicians and the public. The indiscriminate use of antimicrobial agents to treat non-bacterial infections should be contained. The public must be educated to understand that antimicrobial agents are ineffective against viral infections. In the setting of managed care, educating administrators who make practice decisions that cheaper is not always better will be crucial. The issues of day-care infections and spread of potential pathogens must take on increasing attention and methods to decrease infection sought. Curbing inappropriate use of antimicrobial agents will be as important as learning the nuances between new agents.

Single-dose pharmacokinetics of piperacillin and tazobactam in infants and children

The pharmacokinetics of piperacillin and tazobactam were assessed after single-dose administration to 47 infants and children. Study subjects ranging in age from 2 months to 12 years were randomized to receive one of two different doses of a piperacillin-tazobactam combination (8:1): a low dose (n = 23) of 50 and 6.25 mg of piperacillin and tazobactam per kg of body weight, respectively, or a high dose (n = 24) of 100 and 12.5 mg, respectively. The pharmacokinetic behavior of tazobactam was very similar to that observed for piperacillin, supporting the use of these two agents in a fixed-dose combination. No differences in the pharmacokinetics of piperacillin or tazobactam were observed between the two doses administered. The elimination parameters half-life and total body clearance decreased and increased, respectively, with increasing age, whereas volume parameters (volume of distribution and steady-state volume of distribution) remained relatively constant for both compounds. The primary metabolite of tazobactam, metabolite M1, was measurable in the plasma of 18 of the 47 study subjects; 17 of these 18 subjects received the high doses. More than 70% of the administered piperacillin and tazobactam doses were excreted unchanged in the urine over a 6-h collection period. These data combined with the known in vitro susceptibilities of a broad range of pediatric bacterial pathogens indicate that a dose of 100 mg of piperacillin and 12.5 of mg tazobactam per kg of body weight administered as a fixed-dose combination every 6 to 8 h would be appropriate to initiate clinical efficacy studies in infants and children for the treatment of systemic infections arising outside of the central nervous system.

Glycine inhibition of glutamate evoked-release of norepinephrine in the hypothalamus is strychnine-insensitive

The effects of glycine (GLY), D-serine (D-SER), kynurenic acid (KYN), and 7-Cl kynurenic acid (7-Cl KYN), on the evoked release of endogenous norepinephrine (NE) by L-glutamate (L-GLU) in rat hypothalamic slices was investigated. KYN (500 and 100 microM) and 7-Cl KYN (10 microM) blocked evoked release of NE by L-GLU (1 mM). The inhibitory effects of 100 microM KYN on evoked release of NE by L-GLU were reversed by 10 microM and 100 microM D-SER and, but not 10 or 100 microM GLY. When KYN was not present in the superfusate, superfusion with either 10 or 100 microM GLY alone simultaneously with 1 mM L-GLU blocked the evoked release of NE produced by L-GLU. The addition of strychnine (3 or 100 microM) to the superfusate did not block the inhibitory effects of 10 microM GLY on L-GLU-evoked NE release. These findings suggest that a novel strychnine-resistant GLY receptor is present in the rat hypothalamus.